An initiative to earmark certain city properties for below market-rate housing will go before voters in November, on what has become a ballot already crowded with housing-related measures.

The Board of Supervisors approved an ordinance to place the measure on the ballot Tuesday. The initiative calls for surplus and underutilized city-owned property to be used for the development of below market-rate homes, which would be prioritized for those who are low-income or homeless.

The measure will not apply to parks and open space, or property owned by state and federal agencies. It seeks to maximize the creation of below market-rate homes in keeping with the voter-approved Proposition K, which recommends developers include at least 33 percent below-market-rate units.

“In a city like San Francisco, city-owned sites may be the only opportunity to build new affordable and middle income housing,” Supervisor Jane Kim, who sponsored the ordinance along with Supervisors David Campos, John Avalos and Eric Mar, said in a statement. “The voters were clear with the passage of Proposition K – we need affordable housing now.”

In addition to the surplus city property ordinance, voters will face a number of other housing-related issues on the ballot, including a proposed moratorium on market-rate housing in the Mission, a $310 million housing bond, stricter controls of short-term housing rentals, and a measure that seeks to raise the height limit for a mixed-use development along the waterfront just south of AT&T Park.